//
// NotificationStrategy.h
//
// Library: Foundation
// Package: Events
// Module:  NotificationStrategy
//
// Definition of the NotificationStrategy interface.
//
// Copyright (c) 2006-2011, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_NotificationStrategy_INCLUDED
#define Foundation_NotificationStrategy_INCLUDED


#include "Poco/Foundation.h"


namespace Poco
{


template <class TArgs, class TDelegate>
class NotificationStrategy
/// The interface that all notification strategies must implement.
///
/// Note: Event is based on policy-driven design, so every strategy implementation
/// must provide all the methods from this interface (otherwise: compile errors)
/// but does not need to inherit from NotificationStrategy.
{
public:
    typedef TDelegate * DelegateHandle;

    NotificationStrategy() { }

    virtual ~NotificationStrategy() { }

    virtual void notify(const void * sender, TArgs & arguments) = 0;
    /// Sends a notification to all registered delegates.

    virtual DelegateHandle add(const TDelegate & delegate) = 0;
    /// Adds a delegate to the strategy.

    virtual void remove(const TDelegate & delegate) = 0;
    /// Removes a delegate from the strategy, if found.
    /// Does nothing if the delegate has not been added.

    virtual void remove(DelegateHandle delegateHandle) = 0;
    /// Removes a delegate from the strategy, if found.
    /// Does nothing if the delegate has not been added.

    virtual void clear() = 0;
    /// Removes all delegates from the strategy.

    virtual bool empty() const = 0;
    /// Returns false if the strategy contains at least one delegate.
};


template <class TDelegate>
class NotificationStrategy<void, TDelegate>
/// The interface that all notification strategies must implement.
///
/// Note: Event is based on policy-driven design, so every strategy implementation
/// must provide all the methods from this interface (otherwise: compile errors)
/// but does not need to inherit from NotificationStrategy.
{
public:
    typedef TDelegate * DelegateHandle;

    NotificationStrategy() { }

    virtual ~NotificationStrategy() { }

    virtual void notify(const void * sender) = 0;
    /// Sends a notification to all registered delegates.

    virtual DelegateHandle add(const TDelegate & delegate) = 0;
    /// Adds a delegate to the strategy.

    virtual void remove(const TDelegate & delegate) = 0;
    /// Removes a delegate from the strategy, if found.
    /// Does nothing if the delegate has not been added.

    virtual void remove(DelegateHandle delegateHandle) = 0;
    /// Removes a delegate from the strategy, if found.
    /// Does nothing if the delegate has not been added.

    virtual void clear() = 0;
    /// Removes all delegates from the strategy.

    virtual bool empty() const = 0;
    /// Returns false if the strategy contains at least one delegate.
};


} // namespace Poco


#endif // Foundation_NotificationStrategy_INCLUDED
